Study On Prevalence And Subtypes Of Blastocystis Sp.from Calves In Partial Areas Of Shaanxi Province

Cattle is an important economic animal with important position in the animal husbandry.However,due to the inadequate sanitary conditions and management measures of the farms,several pathogenic infections occurred.Among them,Blastocystis,a common single-celled pathogenic microorganism,possess wide range of hosts and inhabits in intestinal tracts of humans and various animals.Although there are still some controversies on the taxonomy,life history and pathogenic mechanism of Blastocystis,in vitro and experimental animal studies have shown the potential pathogenesis of Blastocystis in young and immunocompromised hosts.Previous studies also reported the infection of Blastocystis in faecal samples of hosts with diarrhea or other gastrointestinal symptoms.Additionally,the colonization of Blastocystis has been identified to be associated with some intestinal diseases of hosts,particularly with irritable bowel syndrome(IBS).Recent studies also indicated the close relationships of colonization of Blastocystis with intestinal health and immunity of hosts.The presence and genetic diversity of Blastocystis in cattle were revealed by using molecular biological analysis based on the ribosomal small subunit(SSU rRNA)gene.At present,of seven subtypes(ST1,ST3,ST4,ST5,ST6,ST10,and ST14)reported in cattle,five(ST1,ST3,ST4,ST5,and ST6)are zoonotic subtypes.Thus,clarifying the infection status of Blastocystis in cattle not only provides the fundamental data for the health of herds,but also can be used to evaluated the zoonotic potiential of Blastocystis infection in the local humans.Therefore,in the present study,faecal samples of 198 dairy and 173 Qinchuan calves were collected from six geographical regions of Shaanxi province,including Yangling,Tongchuan,Hanzhong,Weinan,Baoji,and Xianyang,and the prevalence and subtypes were systematically examined for these samples using molecular biological methods based on the SSU rRNA genes.The zoonotic potential was also evaluated for these animals.The results indicated that approximately 600 bp target gene fragments were observed in 216 samples faecal samples of calves,but only 92 were identified to be Blastocystis by sequencing with the total prevalence of 24.8%(92/371).The highest prevalence was detected in Baoji city(48.0%,59/123),followed by Weinan(26.7%,4/15)and Yangling(15.0%,24/160),while no infections were found in Hanzhong.The prevalence of Qinchuan calves(27.2%,47/173)was slightly higher than that of dairy calves(22.7%,45/198),but the difference was not significant.The prevalence of post-weaned calves(38.6%,66/171)was significantly(P < 0.01)higher than that of pre-weaned calves(13.0%,26/200).Phylogenetic analysis based on the SSU rRNA gene indicated that four subtypes were detected in calves of the present study,namely ST4,ST5,ST10 and ST14.Among them,the ST10 was identified as the predominant subtype(38.5%)and widely distributed in all age groups and positive areas of calves.The zoonotic ST4 and ST5 subtypes mainly distributed in pre-weaned dairy calves of Xianyang,Baoji,and Weinan,while the subtype ST14 was mainly detected in dairy calves and Qinchuan calves from Yangling,Baoji,and Tongchuan.Collectively,the existence of Blastocystis infection was observed in calves from partial areas of Shaanxi province,and their prevalence was closely related with geographical distribution and ages of calves.Subtype analysis indicated genetic diversity of Blastocystis in calves from partial areas of Shaanxi province,with two zoonotic(ST4 and ST5)and two animal-specific subtypes(ST10 and ST14)detected.These findings suggested that comprehensive control measures would be implemented to control Blastocystis infection of calves in Shaanxi province and effective treatment should be established to prevent Blastocystis infection from calves to other animals and humans.